17

Kayla Carpenter, Cat Garcia, and Cameron Norton

Abstract

The lionfish have threatened the population of Atlantic native fish and the well-being of coral reefs in the area since their introduction in the 1980s. This chapter assesses causes, consequences, and solutions to help mitigate the negative effects caused by the lionfish to restore Atlantic waters.

Framing of the Problem

The population of Atlantic native fish and the health of the coral reefs are seeing a rapid decline due to an alien invader: The lionfish. This majestic fish, which is native to Pacific ecosystems, was introduced into the Atlantic by irresponsible pet owners who released them into the ocean. The lionfish first appeared off the coast of Florida in the mid-1980s but quickly spread all across the east coast, the Gulf of Mexico, and the Caribbean (Hixon, 2011). Due to the aggressive nature of the lionfish, they are able to rapidly eat the majority of reef fish that likewise belong to the diets of native fish, leaving them no food to prey on. This huge appetite has caused many fish to become harder to spot, causing fisheries in the area to suffer economically. This inability to catch and sell fish in return for money has threatened the comfort as well as the security of those living near the affected areas. Lionfish also feed on herbivorous fish that keep the algal growth on coral reefs at bay which has caused the reefs to rot, destroying the shelter for many other marine creatures.

The lionfish in the Atlantic area are causing a severe negative downfall in their ecosystem. They are indirectly causing one of the most dangerous situations the Atlantic waters have ever experienced and driving native fish and plants to local extinction. In just a 5 week span, lionfish are said to reduce the population of native sea creatures by 80% to 90% (Lionfish Central, 2020), which in turn is destroying the coral reefs. They are consuming more reef fish than any other predator in the Atlantic due to their large stomach capacity, causing a decrease in the population of small reef fish and larger native fish who feed on these smaller prey fish. Without the range of algae-eating fish, coral reefs are also starting to crumble. Atlantic native fish and coral reefs are already in danger due to overfishing and climate change, but soon enough the lionfish will drive them to extinction in the Atlantic and rid the area of biodiversity.

Background

The Lionfish

Pterois volitans, better known by the name Red Lionfish, is a venomous predatory coral reef fish of the family Scorpaenidae. It is characterized by its most dominant features, red and white stripes covering its body, long extravagant fins, and large mouths. These fish can grow to be between twelve and fifteen inches long at maturity and can weigh around one to two kilograms. The Red Lionfish is adorned with many venomous spines on its back and fins. A “sting from the red lionfish constitutes a serious health emergency,” which in many cases can require hospitalization (Robins, 2017). Many symptoms of the venomous sting include headache, nausea, and swelling, but can escalate to more severe issues such as pulmonary edema, muscle paralysis, and loss of consciousness. Lionfish are known to be aggressive and can charge at their prey with their spines revealed, often cornering them against a part of the reef. In humans, they “rank second only to stingrays in the total number of envenomations, with an estimated occurrence of approximately 40,000 – 50,000 cases annually”  (Robins, 2017).

Lionfish are highly predatory and will typically consume small species of fish, but have been reported to consume larger fish and crustaceans as well. They are effective predators, chasing their prey into a corner before snapping them up with incredible speed. In addition, these fish are very intelligent and use their coloration to blend in with their surroundings. Most notably, lionfish “prefer living near rocky coral areas where they can hunt small fish and invertebrates, and then retreat into crevasses” and are masters at hiding, where they are practically undetectable by other fish (Robins, 2017).

Species Introduction

The lionfish originated in Pacific reef ecosystems, but since their introduction to the Atlantic, they have spread quickly. The primary reason behind the introduction of the lionfish to the Atlantic was caused by “human-mediated introduction through the ornamental fish trade” which has led to extreme ecological damage (Bariche et al., 2017). Since the introduction of the species, the Indo-Pacific lionfish has been sighted in numerous Atlantic regions, primarily thriving in the southeastern region including the Floridian coast and the Bahamas. The survival of the lionfish is dependent on multiple factors such as temperature and predation or lack thereof. Lionfish are commonly observed in the southeastern United States continental shelf, spanning from southern North Carolina to the south tip of Florida. The waters in this region are “relatively saline (34 to 36 salinity) and warm (12 to 16 C winter minimum), which can allow for temperate marine fauna to survive and reproduce (Whitfield, 2002).  They have also colonized large areas of the Caribbean and Western Atlantic,” (Bariche et al., 2017). Many theories lead to the introduction of these fish in the Caribbean, but the most likely theory is “an arrival through the Suez Canal” caused by larva transport through a current (Bariche et al., 2017). With the fish present in the majority of the Atlantic, many species of flora and fauna are now in danger.

Many early efforts to assess the population of lionfish “suggested that lionfish populations were rapidly increasing, with trophic interactions with native reef fishes a concern” (Morris & Akins, 2009). With the lionfish now residing in Atlantic reef ecosystems, many species of Atlantic fish have faced a severe decline. Unfortunately, because lionfish are non-native to Atlantic ecosystems, Atlantic fish lack an understanding of the predation that lionfish inflict on ecosystems (PBS NewsHour, 2016). The lionfish is a sustainable hunter in the Pacific since fish in surrounding habitats know to avoid it, but in the Atlantic, it gorges itself and consumes far too much since surrounding prey have no instinct to avoid the fish. Many lionfish, upon gastrointestinal examination, were known to prey upon crustaceans but also prey upon many species of fish that aid in reef health and maintenance. The lionfish invasion has “increased swiftly between 2004 and 2010” in the Bahamas and between 2008 and 2010, “lionfish increased from 23% to nearly 40% of the total biomass of predators” which demonstrates the rapid rate of decline in native species (Green et al., 2012). Many small species of fish are consumed by lionfish, but often larger species are consumed as juveniles as well and these larger species could include predators or larger algae eating fish. An example of a smaller fish preyed upon by the lionfish is a critically endangered fish known as the social wrasse, which is a planktivore that is one of five coral reef fish species in immediate danger of extinction (Rocha et al., 2015).

Detriment to Coral Reefs

Coral reefs are suffering due to the immense predation that lionfish inflict upon their ecosystems as well. In the Bahamas, “lionfish have extended their habitat range into mesophotic depths down to 91 meters where they have reduced the diversity of several important fish” who are important to maintaining algae growth on the corals (Lesser & Slattery, 2011). In addition, there has been a significant loss of coral diversity due to algae growth, and because the herbivorous fish responsible for cleaning the corals are becoming endangered and declining at a fast rate, the growth is becoming unmanageable.

Many reefs, specifically mesophotic reefs, are high-density sheltered hubs for a variety of species of the flora and fauna biota. In the Bahamas specifically, mesophotic reefs are known for their algal-dominated coral formations and the presence of the herbivores that keep the growth at bay. Lionfish have been spotted at depths up to 300 feet below the surface, where reefs with a “>50% benthic cover” are common (Lesser & Slattery, 2011). This high density of lionfish has resulted in the decline of herbivorous fish and sponges, causing algal growth to dominate the reef. According to an article by Michael P. Lesser, the phase shift between coral and algal dominance is prevalent and, “the timeframe of that shift depends on the level of coral recruitment in the system, as well as the intensity of herbivory and the structure of the herbivore guild” and due to the abnormal rate of predation by the lionfish, coral recruitment is at an extreme low.

A study conducted in Bock Wall from the year 2003, when lionfish first began moving to the region, to 2009 was performed by observing the structure of the coral reef ecosystem. By the end of the study, it was concluded that “percent algal cover at 46 m was 27% in 2003, 31% in 2005 and 94% in 2009,” demonstrating the impact that lionfish had on the reef since their arrival (Lesser & Slattery, 2011).

Economic Impact

From these invasions, other problems have arisen in areas that rely on fishing. In areas, like the Bahamas, the spiny lobster is important to sustain the economy. However, since lionfish have started to appear in that area, the productivity of some of these lobster fisheries has gone down from at least 7% to some estimates of around 13% (Henderson, 2012). This trend has been caused by the abundance of lionfish in certain fisheries, which requires individuals to take them out or kill them. This has caused major concern for certain fisheries, as it shows that lionfish have the power to economically impact businesses, especially on islands.  (Henderson, 2012).

Intellectual Merit

Our research examines the negative effects that lionfish are indirectly causing in the Atlantic and assesses effective solutions to help mitigate these issues. The main question that guided our research into this problem was: What measures need to take place to ensure the safety of the native fish populations and coral reefs in the Atlantic? This research could become crucial in saving certain populations of native fish that live in coral reefs as well as improve the financial stability of the Atlantic fisheries. Ecological sciences play a vital role in this research due to the fact that the lionfish are destroying coral reefs and have the potential to cause native fish to become extinct. A better understanding of the relationship between lionfish and its surrounding provides insight into their aggressive nature and their effect on other organisms. With this decrease in the native fish population, there are fewer fish for humans to hunt and sell. Local fisheries are not catching as many fish due to complications between the native fish and the lionfish, which is causing the financial stability of the communities in the area to be at risk, which ties in the role of economics. When studying how the economy relates to the situation with the lionfish, those studying in this field have a better understanding of how the financial standpoint of the communities in the area is declining. Without the abundance of fish for people to eat, social sciences will be involved because the comfort and security of those living near these affected areas will no longer be stable. Different social sciences will have the opportunity to come together in order to research this issue in more depth in order to help the community thrive.

Methodology

In order to execute this research, the group reviewed scholarly, peer-reviewed materials that are related to the topic. This included papers written by professors, maps and models of the situation, legal documents, and other scholarly sources that help the group get a greater picture of how the lionfish are causing species to go extinct. In addition, part of the research was done by interviewing experts in lionfish, conserving species affected by these invasive creatures, and limiting their impact. The interviews were done mostly through email, though other alternatives were available if they agreed. This does not include, however, experiments that could have been done by the group, as COVID-19 has hindered the ability to perform such tasks. Once the data was all collected, the group wrote a paper with all the details in it, a poster that easily shows the findings to the public, and a presentation that is a combination of both the previously stated creations.

Findings and Results

While it is true that the lionfish invasion has no perfect solution, there are a variety of current and future approaches that could aid in the restoration of the Atlantic ecosystems. A prominent solution that is currently being used is the targeted killing and removal of lionfish in Atlantic reef ecosystems. This method is performed in many regions along the Caribbean including the Floridian coast, the Bahamas, and the Gulf of Mexico. Many events take place in these regions to curb the effects of invasive lionfish which include diver-led targeting practices and lionfish derbies. Lionfish derbies are competitive events that encourage dive teams to hunt and kill as many lionfish as they can in one day. These events are an effective way to encourage the community to get involved in the eradication of this dangerously invasive species. According to the NOAA, “recent efforts to focus collections by divers has resulted in over 1400 lionfish collected in one day during derby-style events” especially in areas where lionfish are highly concentrated on reefs (Morris & Whitfield, 2009). 

One possible solution is the introduction of traps to contain lionfish for removal. However, according to Dr. Exton, this method comes with numerous ethical concerns due to the possibility of trapping and killing species other than the Red Lionfish. In order to not contribute to the decline of native species, a fish trap must exclusively capture lionfish, which is nearly impossible. Though they are not quite feasible, lionfish traps could be a cost-effective solution to the issue. They can cover wide areas of the seafloor and can collect numerous lionfish at once. Research is underway to determine a more effective lionfish trap, such as an option to allow small fish to swim out of the trap if caught, and an option to tangle the lionfish’s venomous spines to prevent harm to other fish as well as divers.

Guardian LS-1

Dr. Dan Exton, a marine biologist at Operation Wallacea, participated in many dive expeditions and targeted killing on the coast of Honduras, where lionfish are very prevalent. In an interview, he addressed the concern that lionfish now exist at depths of up to 1200 feet. These individuals have adapted reproductively to lay as many as 2 million eggs per year. Because of the prevalence of lionfish in such deep waters, lionfish derbies and diver-facilitated killings become increasingly difficult and not feasible due to a variety of reasons. For one, the gas emitted at that depth can be harmful to divers, and the pressure from the water can impact the well-being of the divers involved as well. To combat this, Dr. Exton and his team have explored a variety of solutions to combat the recent invasion of the species in such deep water.

Due to concerns about traps designed to capture lionfish, Dr. Exton and his team are collaborating to form a new type of solution. At a chapter of iRobot near Boston, researchers and engineers alike are collaborating on the invention of a robot that can capture lionfish with ease. This robot is currently being developed by researchers at Robots in Service to the Environment (RSE), an organization founded by Colin Angle of iRobot. The robot, known as the Guardian LS1, has many different parts that contribute to capturing and securing lionfish for capture. As shown in the figure, part one consists of stunning panels with “low controlled voltage” that “temporarily stuns the lionfish long enough to be captured” (RSE, 2019). To pair with the stunning panels, a thruster mechanism is mounted to quickly capture the lionfish and place them in a chamber fitted with a retention feature. It is mounted with a number of additional features for added stability such as, “8 thruster array for total motion control, allowing complex hunting maneuvers and stabilization of undersea currents” along with pressure safe containment of electronics to amplify the effectiveness of the device (RSE, 2019). According to the RSE, the critical breeding depth is 150-500 feet. The Guardian LS1 is capable of achieving depths of up to 700 feet, able to capture the majority of the lionfish present in this critical area.

Culinary Applications

Though there is no perfect answer to the lionfish problem, a solution exists that includes fisheries, restaurants, and members of the general public alike. Consuming lionfish for culinary purposes was found to have significant economic and ecological benefits regarding the issue. Often, at the end of a day-long lionfish derby in the Caribbean, local restaurants along the coast gather together to cook a variety of recipes using lionfish as a way to come together and celebrate the end of a hard day’s work.

Lionfish is described to have a light flavor and a flaky texture. Because it is mild, it can be prepared in many different ways and is suitable for many recipes. Besides its great taste, lionfish meat is known to have numerous health benefits when consumed. Compared to other fish such as grouper and tilapia, the lionfish is very high in n-3 fatty acids which are known to greatly improve heart health and lower the risk for heart attack or other heart diseases. The primary fatty acids found within lionfish are n-6 and n-3 polyunsaturated fatty acids, with a mean fillet yield of, “30.5% of the total body wet weight, a value that is similar to that of some grouper and porgy species” (Morris et al., 2011).

Resources

Bariche, M., Kleitou, P., Kalogirou, S., & Bernardi, G. (2017). Genetics reveal the identity and origin of the lionfish invasion in the Mediterranean Sea. Scientific Reports, 7(1), 6782–6786. https://doi.org/10.1038/s41598-017-07326-1

Green, S.J., Akins, J.L., Maljković, A., & Côté, I.M. (2012). Invasive lionfish drive Atlantic coral reef fish declines. PLoS ONE, 7(3), e32596. https://doi.org/10.1371/journal.pone.0032596

Henderson, E.B. (2012). Economic and ecological implications of interactions between lobsters and invasive lionfish in the Bahamas. [Honors Thesis]. Simon Fraser University. Retrieved from https://summit.sfu.ca/item/12558

Hixon, M. (2011, December 17). How will you prevent an alien invasion? TEDxYouth@SanDiego. [Video] YouTube. https://youtu.be/YiMTGAbCRV8.

Lesser, M.P., & Slattery, M. (2011). Phase shift to algal dominated communities at mesophotic depths associated with lionfish (Pterois volitans) invasion on a Bahamian coral reef. Biological Invasions, 13(8), 1855–1868. https://doi.org/10.1007/s10530-011-0005-z

Lionfish Central. (2020). Lionfish FAQs. Retrieved from https://lionfishcentral.org/lionfish-frequently-asked-questions/.

Morris, J.A., & Akins, J.L. (2009). Feeding ecology of invasive lionfish (Pterois volitans) in the Bahamian archipelago. Environmental Biology of Fishes, 86(3), 389. https://doi.org/10.1007/s10641-009-9538-8.

Morris, J.A., Jr., & Whitfield, P.E. (2009). Biology, ecology, control and management of the invasive Indo-Pacific lionfish: An updated integrated assessment. NOAA Technical Memorandum NOS NCCOS 99. 57 pp. Retrieved from https://aquadocs.org/bitstream/handle/1834/20632/NCCOS_TM_99.pdf?sequence=1&isAllowed=y

Morris, J.A., Thomas, A., Rhyne, A.L., Breen, N., Akins, J.L., & Nash, B. (2011). Nutritional properties of the invasive lionfish: a delicious and nutritious approach for controlling the invasion. AACL BIOFLUX, 4(1).

PBS NewsHour (2016, August 21). How Florida is handling invasive lionfish [Video]. YouTube. https://youtu.be/CSd7pgvOV3M.

Robins, R. (2017, May 11). Red Lionfish. Pterois volitans. Florida Museum. Retrieved December 08, 2020, from https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/pterois-volitans/

Rocha, L.A., Rocha, C.R., Baldwin, C.C., Weigt, L.A., & McField, M. (2015). Invasive lionfish preying on critically endangered reef fish. Coral Reefs 34, 803–806. https://doi.org/10.1007/s00338-015-1293-z

RSE (Robots in Service of the Environment). (2019). The Guardian Solution. Retrieved December 10, 2020, from RSE: Robots In Service of the Environment | Lionfish Project (robotsise.org)

Whitfield, P., Gardner, T., Vives, S., Gilligan, M., Ray, W. C., Ray, G., & Hare, J. (2002). Biological invasion of the Indo-Pacific lionfish Pterois volitans along the Atlantic coast of North America. Marine Ecology Progress Series, 235, 289-297. https://doi.org/10.3354/meps235289